Project Summary/Abstract This proposal presents a 5-year research career development program focused on the study of Bacille Calmette- Guérin (BCG) vaccine and the mechanisms of innate immune memory, otherwise known as trained immunity, underlying its observed, pathogen-agnostic, protective health effects in early life. The candidate is currently an Instructor of Pediatrics at Harvard Medical School in the Department of Neonatology at Beth Israel Deaconess Medical Center, and Associate Scientist at the Precision Vaccines Program in Boston Children’s Hospital (BCH). The outlined proposal builds on the candidate’s previous research on in vitro modeling of human leukocyte responses to BCG vaccine formulations and complements her clinical training as a Neonatologist. Under the mentorship of Dr. Ofer Levy, a human immunology and vaccinology expert at BCH, and complementary guidance by an Advisory Committee, the candidate will characterize novel immunometabolic mechanisms of BCG vaccine- induced trained immunity in newborns. The proposed experiments and didactic work will provide the candidate with a unique intellectual framework and skill set at the intersection of newborn immunology, trained immunity and systems biology that will facilitate her transition to independence as a translational pediatric vaccinologist. Infectious diseases are leading causes of neonatal morbidity and mortality, due in part to a distinct immune system at this developmental stage. The live attenuated Mycobacterium bovis vaccine BCG is given at birth to millions of newborns worldwide to prevent severe forms of tuberculosis (TB). Epidemiologic studies demonstrate that BCG confers a mortality benefit to immunized newborns when administered early in life, attributed to protection vs. non-TB respiratory infections and sepsis. The mechanisms underlying BCG beneficial health effects in early life are incompletely characterized, while in adults epigenetic and metabolic reprogramming of monocytes have been implicated. This proposal will investigate the immunometabolic signatures of BCG-induced trained immunity in human newborns, who manifest distinct immunity and bioenergetic demands. The proposed study is based on preliminary data demonstrating distinct immunometabolic rewiring in human newborns and their leukocytes after BCG immunization producing key age-specific signatures of BCG-induced trained immunity. More specifically, the aims of this proposal are to: 1) Characterize BCG-induced immunometabolic pathways of trained immunity in human newborn monocytes using a novel in vitro platform established by the candidate; 2) Leverage an in vivo cohort to identify and validate metabolic pathways that may drive trained immunity in BCG-immunized human neonates; and 3) Mechanistically probe age-specific metabolic pathways of BCG-induced trained immunity in vitro. The proposed project, linking expertise in neonatology, immunology, metabolism, vaccinology and systems biology will dissect cellular and molecular mechanisms of BCG-induced trained immunity in early life, thereby providing fresh insights to inform future early life vaccine development.

Project Narrative Infectious diseases are leading causes of death in newborns who have distinct immunity and metabolic needs. Vaccines are the most effective biomedical intervention to prevent infection and may confer off-target health benefits, but the mechanisms by which they do so are incompletely characterized in early life. The proposed research will explore the effects of Bacille Calmette-Guérin (BCG) vaccine, given yearly to ~150 million newborns across the globe, on neonatal immunity and cellular metabolism to identify molecular signatures of broad vaccine protection against infection that can be harnessed to optimize current and future vaccines tailored to the very young.